Method and device for processing a teat rubber during production

ABSTRACT

During the production of teat rubbers, in particular of teat rubbers containing a high percentage of silicone, pressure is applied when the teat rubber preforms are removed, the radial expansion of teat rubber areas being appropriately limited to a maximum value. Hence, the removal can be executed automatically and at a comparatively high temperature without irreversible damage being caused to the material. The removal process can be supported by an appropriate contact surface whose contour corresponds, at least partially, to the outer contour of the preform. Furthermore, an appropriate removal device is provided.

RELATED APPLICATION

This application is a divisional of U.S. application Ser. No.12/449,136, which is the National Stage of International Application No.PCT/EP2008/000472, filed Jan. 22, 2008, which are hereby incorporated byreference, and claims the benefit of German application no. 10 2007 003480.8 filed Jan. 24, 2007.

FIELD OF THE INVENTION

The present invention relates in general to the field of mechanicalmilking of dairy animals and in particular to the production of teatrubbers which are to be applied to the teats of the animals in automaticor semi-automatic milking processes.

BACKGROUND OF THE INVENTION

Modern agriculture is determined by high pressure of competition whichis further intensified by the increasing globalization. In particular indairy farming great value is therefore placed on high profitability inthe production of milk. For this purpose, however, it is particularlyimportant to aim at a certain degree of automation in the production ofmilk and therefore allow attending to a huge stock of animals with a notexcessively large amount of staff. Furthermore, the quality of thegained milk must have a high standard and it is also essential that therespective national and international regulations regarding the qualityof the milk are carefully observed. A very important aspect of achievinga permanently high yield of milk is to be seen in keeping the health ofthe animals in a herd at a high level, so that, in the long run, thehighest possible yield of milk can be obtained from every single animal.

During increasing automation in attending to a great number of milkanimals certain milking methods have become accepted in the past, which,on the one hand, aim at allowing to attend to and therefore also milk agreat number of animals with a small amount of staff being required and,on the other hand, provide surroundings for the animals which are asoptimal as possible to ensure the health of the animals in the log run.For this purpose, so-called milking robots are used in many largeagricultural farms where, for example, the milking process is almostfully automated, so that normally more than two milking processes perday can be accomplished on one individual animal, the number of personsrequired being low. On other farms, a semi-automatic milking strategy isapplied, which involves the use of so-called milking parlours wherecertain activities are carried out or at least supervised by the staff,and merely the milking process itself is almost fully automated.

Depending on the process strategy, the milking process itself isnormally carried out such that after a certain stimulation phase anegative pressure is generated at the respective teat, so that milk flowoccurs, with a massage action interrupting the milking flow at regularintervals being typically carried out. To this end, pressure fromoutside is applied to the teat at regular intervals, so that a certainbackward flow of blood and lymph takes place during this phase and alsoappropriate pressure conditions are generated at the teat, which atleast roughly imitate the natural sucking behaviour of a calf. Themilking function and, in part or completely, the function of stimulationbefore, during and after the actual milking process are executed in acontrolled manner with the aid of a milking equipment, which hasrespective teat cups, with the support of a qualified person orcompletely automatically. The individual teat cups are normallyimplemented as rigid cups backed on the inner side with an elasticmaterial, the so-called teat rubber. Hence, the teat rubber is in directcontact with the teat of the animal and thus, in a certain way,represents an “interface” between animal and machine. Therefore, theteat rubber must have a plurality of properties to comply with therequirements occurring in automated milking, viz, the teat rubber mustfirst of all allow appropriate pressure conditions to be obtained underthe teat to start the desired milk flow. Hence, the teat rubber must beadapted to be slipped on the teat on the one hand and, nevertheless,must generate a sufficiently high leak tightness at the teat bottom tothus allow the generation of the desired negative pressure.

Furthermore, in the desired periodic interruption of the milk flow andthe resultant massage action, there must be a sufficiently highelasticity to ensure folding in or collapsing of the teat rubber belowthe teat. This is accomplished by applying (pressurized) air to theoutside of the teat rubber. In this connection, frequencies ofapproximately 0.2 to 2 Hz are normally obtained, so that throughout itsservice life the respective material of the teat rubber is to accomplisha multitude of folding processes with almost equal behaviour.Furthermore, the teat rubber must, all in all, show a good cleaningbehaviour, since nucleation must be suppressed to the highest possibledegree, so that bacteria will be prevented from being transmitted fromone animal to the other to a very large extent. Furthermore, thematerial must be as inert as possible from a chemical view-point, sothat material will not be separated into the milk and, hence, the highstandards in terms of hygiene and quality will be observed.

As a result of the many criteria to be met by a teat rubber, a pluralityof material mixtures is presently in use; normally, appropriate polymermaterials are employed in the production of teat rubbers. Therefore, thediverse materials can produce very different results with respect todurability, efficiency as regards high yield and particularly withrespect to the health of the animals. In particular, with regard to thelast-mentioned aspects, consistency and material properties proved to beimportant characteristics to increase the milking process efficiency.For instance, relatively soft materials, for example, silicone mixtures,are advantageous for a high yield and milk health, since a contact areathat is comfortable for the animal or an “interface” between animal andmachine in the milking process can be created in this way. Hence,respective mechanical strain as well as the resultant hardening andpathological change of the teat can be suppressed significantly incontrast to relatively hard rubber mixtures.

As a result of the many different requirements to be met by a teatrubber, teat rubbers in use must be exchanged relatively often, so thatefficient production methods are required in which the teat rubbers areproduced efficiently in great number and with constantly high quality.The teat rubbers are normally produced from a polymer material mixtureunder pressure and heat on the basis of an appropriate mould by means ofan injection moulding process. In this manufacturing process, thecorresponding material mixture is heated and thus assumes a viscousstate and, under a relatively high pressure, the latter is injected intoa corresponding mould where, after a certain curing time, a respectivepreform of the teat rubber is formed which is then removed from themould and subjected in a suitable manner to a finishing treatment so asto obtain the final state of the teat rubber. To achieve anappropriately efficient production of the teat rubber, material mixturesare frequently used, which allow an efficient manufacturing process,particularly during the removal of the still hot preform. Normally,harder material mixtures allow a better handling, since they are of ahigher mechanical stability. In the processing of material mixturesresulting in a relatively soft teat rubber, e.g. silicone teat rubbers,the removal of the teat rubber preform from respective components of theinjection mould is a critical process, since an excessive mechanicalstrain or any other form of excessive deformation can result in anirreversible modification of the material of the preform and can thusmake the teat rubber unusable. For allowing a wide range of differentmaterial mixtures and particularly soft mixtures of material, which canbe advantageous in the use of the teat rubbers, to be efficientlyprocessed in the production process, suitable measures are thereforerequired to avoid, as far as possible, irreversible modifications of theteat rubber material after the injection moulding and before thefinishing treatment.

SUMMARY OF THE INVENTION

With respect to the above-mentioned problem, a method of producing teatrubbers is provided according to one aspect of the present invention,said teat rubber having a head area and an adjoining tubular area. Themethod comprises the steps of forming a preform of the teat rubber froma heated polymer material mixture by means of a mould, and removing thepreform from a mould element which determines, at least partially, theinner contour of the teat rubber. The removal is accomplished byintroducing a pressurized fluid into the tubular area and bysimultaneously limiting a radial expansion of the tubular area, causedby the fluid pressure, to a predetermined range.

Making use of this measure, the teat rubber preform can therefore beacted upon by the pressurized fluid from inside and thus be separatedfrom the respective mould element to a certain degree, without any riskof an irreversible deformation of the material in the tubular area ofthe teat rubber. Since the respective elastic limits of the variousmaterial mixtures are well known, or can be ascertained, a suitablerange for a maximum radial expansion of the tubular area can be selectedindividually according to requirements, so that a large number of verydifferent polymer material mixtures and, in particular, very softmixtures of materials can be processed efficiently.

In a further advantageous embodiment, limiting of the radial expansionis effected by providing a sleeve enclosing the circumference of thetubular area, at least partially, with a specified gap before the fluidis introduced. By using a sleeve an accurately adjustable range can veryefficiently be achieved for the desired radial expansion during theintroduction of the pressurized fluid. It follows that, by arrangingsleeves with different dimensions, different requirements of the variousmaterial mixtures can be complied with in a simple manner, so that theprocessing of very hard and also very soft polymer material mixtures,viz, the removal of respective moulded parts, is possible. In otherillustrative embodiments, the radial expansion during pressureapplication is accomplished by other suitable limiting surfaces, whichare arranged around at least the tubular area such that a relativelylarge area of the expanding outer surface of the tubular area iscovered. However, respective spaces between individual portions of thelimiting surface may also be formed, whose size is, however, dimensionedsuch that an excessive expansion of the tubular area material will notoccur in these small spaces.

According to a further illustrative embodiment, the removal of thepreform comprises bringing a part of the preform into contact with acontact surface adapted to the contour of said part of the preform, andapplying a pulling force by means of the contact surface. If necessary,a relatively high pulling force, e.g. in the range of some Newton up tosome 100 Newton, can be applied in this manner so as to remove thepreform, a high adhesion and/or a suitable frictional connection beingachieved by the contoured contact surface.

According to a further illustrative embodiment, the contact surfaceconstitutes part of the inner surface of the sleeve limiting the radialexpansion. Hence, the contact with the inner surface of the sleeveresulting from the application of pressure to the interior of thetubular area can advantageously be utilized to simultaneously increasethe non-positive connection occurring between the outer surface of theexpanding tubular area and the inner surface. A reliable removalbehaviour is achieved in this way, even if relatively long tubularareas, which are completely or in part injected onto the respectivemould element, are produced.

In another embodiment, the radial expansion is limited to 20 mm or less.An irreversible deformation can be prevented for a great group ofpolymer material mixtures by means of such a limitation of the maximumrange of expansion. Advantageously, the radial expansion is adjusted inthis connection to 0.5 mm or more, so that a reliable separation ofadhering tubular areas as well as of the head area from the mouldelement can be accomplished. As a consequence, the adhesion of thepreform to the element of the injection mould determining the innercontour of the teat rubber can be reduced significantly, so that theremoval can then be carried out successfully.

A further advantageous embodiment is so conceived that, for improvingthe sealing characteristics, at least an end portion of the tubular areais mechanically fixed in the radial direction during introduction of thefluid. Hence, by additionally mechanically fixing the end portion, theappropriate working pressure of the fluid to be introduced can beselected relatively high, so that the adhesion to the mould element willefficiently be reduced. Mechanical fixing can be achieved, for example,by bringing into contact appropriate pressure surfaces or by a suitableshape of a respective nozzle for introduction of the pressurized fluid,as will be described hereinafter in more detail.

Mechanical fixing in radial direction further allows an additional axialforce to be applied to the end portion which, at the same time, alsoleads to a compression of at least the tubular area, so that, due to theelastic properties, widening occurs to a certain degree and contributesto a better separation of the mould element.

In a further advantageous embodiment at least the head area has forceapplied thereto by a gripping unit during introduction of the fluid. Bythis application of an appropriate force the effect produced by thepressurized fluid in the head area so as to reduce the adhesion to themould element can be enhanced clearly, because, for example, anappropriate flow path of the fluid through the tubular area in the headarea and out of this area can be produced. On the basis of the resultantflow of the fluid, the further separation of the head area is supportedstill further, so that a reliable removal of the entire preform can beachieved.

A further advantageous embodiment is so conceived that, for introducingthe pressurized fluid, a nozzle provided with a sealing surface is movedto the end portion of the tubular area and pressed onto said endportion. By introducing the fluid in this manner, e.g. the contact forceof the nozzle can be adjusted individually, irrespectively of othermechanical components used for performing the method according to thepresent invention, so that also the sealing behaviour of the nozzle uponintroduction of the fluid can be enhanced. In particular, the sealingsurfaces, in co-operation with the contact force, allow the applicationof relatively high working pressures and thus even larger preforms orstrongly adhering preforms can be separated from the mould element. Forinstance, by process fluctuations occurring during the moulding of thepreform, higher adhesion may occur in some preforms, but, as a result ofthe high adjustable working pressure, a reliable removal willnevertheless be possible. For instance, after a comparatively long downtime or interruption during the injection process, minor temperaturefluctuations can occur in the course of the process, which, in the caseof appropriate material mixtures, will then find expression in increasedadhesion. Hence, changes in the removal behaviour caused by temperaturefluctuations or other process fluctuations are efficiently compensatedby the possibility of applying a high working pressure of the fluid.

In a further embodiment the step of baking out the teat rubber preformfor adjusting the final material characteristics is performed after theremoval process. An appropriate procedure can efficiently be performed,since the preform, which is ready for removal after injection and whichis, in this state, extremely sensitive to mechanical deformation due tothe not yet stabilized molecular structure, can efficiently be removedfrom the mould and can then be subjected to the tempering process. Agreat number of preforms can then be processed simultaneously. In thismanner, the throughput rate of the process for the production of theteat rubber can substantially be adjusted to the cycle predetermined bythe injection moulding unit and thus to the capacity of the latter,since appropriate finishing treatments in the injection mould forstabilizing the preform are not required for enhancing the removalprocess.

According to an advantageous embodiment, the polymer material mixture isa silicone mixture, since the latter has particularly advantageouscharacteristics during the use of the teat rubber, as has been describedhereinbefore. It follows that even sophisticated material mixtures,whose characteristics are soft and therefore favourable for animalhealth and for the efficiency of the milking process, can be processedin an efficient manner, i.e. with a high throughout and with highquality.

According to one embodiment, the preform has a temperature of 150° C. ormore during the removal process. It follows that, on the basis of thistemperature range, the removal process can already take place in a phaseimmediately after injection moulding, since, due to the limitation ofthe radial expansion, the high sensitivity to mechanical deformationoccurring at high temperatures of the preform can effectively becompensated for. This allows a reduction of the throughput time, wherebysystem utilization can be improved, which will also lead to a reductionof the overall cost.

According to another advantageous embodiment, the method comprises thesteps of controlling the fluid pressure and an axial force in such a waythat a predetermined range will be observed for these values. Thecontrol of these two parameters thus allows an efficient adaptation tovarious operating conditions, which may occur e.g. due to fluctuationsin the preceding moulding process and/or due to different polymermaterial mixtures.

According to another advantageous embodiment, the method comprises thesteps of examining whether the preform has been removed successfully,and repeating the removal process, if the preceding removal processshould have failed. In this way, the reliability of the whole productionprocess can be improved substantially, since the removal process inquestion will be repeated in the case of failure, so that, even after anunsuccessful first attempt, the respective part of the mould will againbe available for the further production process within a very shortperiod of time.

According to another advantageous embodiment, at least the fluidpressure is increased during a repeated removal process, so that thestrong adhesion of the preform material to the mould element will beovercome in an efficient manner so as to increase the likelihood thatthe subsequent removal process will be executed successfully.

According to another aspect of the present invention, a device forremoving a teat rubber preform, which comprises a head area and atubular area, is provided. The preform is placed, at least partially, ona mould element determining the inner contour of the teat rubber. Thedevice comprises a removal unit provided with a contact surface which isto be brought into contact with the preform at least partially, and afluid introduction means configured for introducing a pressurized fluidinto the tubular area. Furthermore, the device comprises a limitingdevice for limiting the radial expansion of the tubular area uponintroduction of the fluid.

Making use of this device a radial expansion of at least the tubulararea can successfully be limited to a defined maximum value, so that anirreversible deformation of the material of the preform will be avoided,as has already been explained hereinbefore. It is thus possible tosubject the preform, immediately after injection moulding, to reliablefurther processing so that, in combination with a suitable injectionmoulding system, the device according to the present invention willguarantee high throughout and high quality, since especially thecritical removal process can reliably be executed at high temperaturesin an automated manner.

According to another advantageous embodiment, the limiting devicecomprises a sleeve which encloses the circumference of the tubular areaat least partially, so as to define a gap between the outer surface ofthe tubular area and an inner surface of the sleeve for limiting theradial expansion. The sleeve can be a comparatively stiff unit, whichtherefore predetermines a given diameter and, consequently, also amaximum radial expansion of the tubular area. In other embodiments, thesleeve can be an appropriate arrangement of respective contact surfaces,which, at least during the application of pressure to the tubular area,are moved to an appropriate position close to said tubular area so thatan efficient limitation of the radial expansion is achieved.

According to an advantageous embodiment, the limiting device isconfigured for limiting the radial expansion to 20 mm or less. As hasalready been explained hereinbefore, a maximum expansion can bedetermined for a large range of material mixtures, so that a high degreeof flexibility can be accomplished when the respective polymer materialmixtures are processed. In other embodiments, the limiting device isimplemented such that the radial expansion can be predetermined in anindividually adjustable manner. This also allows different dimensions ofthe teat rubber to be taken into account. To this end, e.g. a largenumber of suitable sleeves having fixedly predetermined dimensions and afixedly predetermined structure can be provided, which are theninstalled in a suitable manner, or the limiting device is provided withsuitable contact surfaces which can be arranged at an adjustabledistance from the tubular area, so that different requirements can becomplied with.

In accordance with an advantageous embodiment, the sleeve is providedwith gas outlets which substantially prevent the formation of gasbubbles between the inner surface of the sleeve and the material of thetubular area during radial expansion of the tubular area. Hence, thematerial of the preform can cling to the inner surface of the sleeve, sothat a high total adhesion can be accomplished between the preform andthe sleeve. The gas outlets can have an arbitrary suitable shape, andmay e.g. be provided in the form of holes, gap-shaped elements and thelike. In some embodiments, the effective area of the gas outlets isdimensioned such that a noticeable “bulging” of the preform materialinto the gas outlet in response to application of the fluid pressurewill be avoided, whereas other embodiments are so conceived that, due toa suitable selection of the area of the openings for given processparameters and characteristics of the preform, the material will bulgeto a certain degree so that the preform will “interlock” with thelimiting surface. It is thus possible to accomplish a very intensivemechanical coupling between the preform and the limiting device, wherebythe removal process will be supported effectively. The dimensioning ofthe size of the gas outlets can be determined by an appropriate testmethod in which the degree of bulging and the reversibility of thedeformation of the preform are examined for various different preformsand operating conditions for the removal process.

According to another advantageous embodiment the limiting device isprovided with a surface which comes into contact with the tubular areaduring a radial expansion of said tubular area and which has adhesion orfriction-supporting surface characteristics. A strong adhesion can thusbe achieved between the limiting surfaces of the limiting device and thetubular area, when pressure is applied to the interior of the preform.The improved adhesion can then be used advantageously for supporting theremoval process.

According to another advantageous embodiment, the limiting deviceadditionally comprises a nozzle which is axially movable relative to themould element, so that the fluid can also be introduced into the tubulararea under comparatively high pressure. In the case of one embodiment,the contact force of the nozzle, which is axially movable relative tothe mould element, can be adjusted as regards the contact between thenozzle and the tubular area, so that appropriately high operatingpressures can be used, which also allow a removal of comparatively largeor long teat rubbers. For example, teat rubbers can be producedefficiently, in the case of which a part of the milk hose, whichprojects beyond the teat cup, is formed integrally with the teat rubber.It is nevertheless possible to accomplish an efficient removal orseparation from the respective parts of the mould. Especially in caseswhere soft polymer material mixtures, e.g. silicone mixtures, are used,a very strong adhesion will be obtained in connection with the heatedmould element. Due to the high operating pressure of the introducedfluid, this strong adhesion can, however, be reduced efficiently.

According to another advantageous embodiment, the surface which comesinto contact with the tubular area constitutes part of the contactsurface used for generating an axial force. Due to the fact that thesurface of the limiting device is used not only for limiting the radialexpansion but also as part of the contact surface, the contour of whichmay therefore also partly correspond to that of the outer surface of thepreform, an efficient non-positive connection can be accomplished so asto allow removal. In particular in the case of large or long teatrubbers, it will be advantageous to use a large-area contact surface forexecuting a more efficient removal of the preform.

According to another advantageous embodiment, the contact surfacecomprises at least a first contact surface region for contacting a headarea of the preform and a second contact surface region for contactingan end portion of the preform. On the basis of this structural design,the head area of the preform, which will normally adhere to an end plateof the injection mould such that it is flush therewith, can be deformedslightly during and/or after the application of the pressurized fluid,so that an adequate fluid flow path will be created in this way, whichleads away from the head area and which will then support the completeseparation of the preform material. In addition, an efficientintroduction of the fluid can be accomplished by the contacting of theend portion, since the sealing characteristics in this area can beimproved in this way.

In accordance with an advantageous embodiment, the first contact surfaceregion is defined by the surface of jaws of a first gripping means andthe second contact surface region is defined by the surface of jaws of asecond gripping means. By providing first and second gripping means, amechanically efficient contact will be established, and it is alsopossible to use cost-efficient and well-proven structural designs.

According to an advantageous embodiment, a third contact surface regionis provided, which is arranged between said first and second contactsurface regions in the longitudinal direction of the tubular area. Inthis way, the axial force required for removing the preform can bedistributed more effectively over the entire length of the preform sothat also teat rubbers of comparatively great length can be processedefficiently.

In accordance with an advantageous embodiment, the contour of the innersurface of the sleeve, i.e. of the device limiting radial expansion,corresponds, at least partially, to the contour of the preform to beremoved. On the basis of this structural design, a frictional connectionwill be accomplished over a very large area when the material expandsradially, so that, all in all, also stronger axial forces can be appliedin the removal process. To this end, the inner surface of the sleeve maybe patterned in a suitable manner, so that a strong frictionalconnection will be accomplished in connection with the elastic preformmaterial clinging thereto. In other cases, the sleeve may be lined withsuitable materials so that an appropriately strong adhesion and/orfriction will be developed in interaction with the material mixture ofthe preform.

In accordance with another preferred further development, the device isconfigured for removing a plurality of preforms at the same time. Thethroughput of the system can in this way be increased in a suitablemanner.

According to another preferred embodiment, a control unit isadditionally provided, which is configured for maintaining the fluidpressure and a pulling force, applied during the removal process, withina specified range. It follows that, by means of said control unit, aprecisely defined operating condition can be maintained. The controlunit is, for example, also able to cause various operating conditionsfor the removal process, if this should become necessary due to processfluctuations and/or different material mixtures during the precedingwork step, so as to compensate different adhesion characteristics duringthe removal.

In accordance with another preferred embodiment, the control unit isadditionally configured for identifying a non-removed preform and forexecuting a specified correction function automatically. In this way,the whole sequence of manufacturing steps for the teat rubber can beexecuted in an automated and therefore extremely economical manner,since the specified correction function can be specified such that theoverall system will only be influenced to a minor extent. For example,an appropriate alarm function can be provided, so that an operator ofthe system will be informed. In the case of one embodiment, thecorrection function includes a repetition of the removal process. In thecourse of this repetition, different operating parameters may be usedfor the removal, so as to accomplish now a reliable separation of thepreform material from the mould element. If necessary, it is alsopossible to use operating parameters which may perhaps impair thepreform, but which allow a reliable removal of the preform. For example,at least the fluid pressure can be increased so as to successfullyremove a strongly adhering preform. Since the removal process inquestion will normally be significantly shorter than the respectiveprocess for producing the preform, the automatic repetition of theremoval process will only contribute to a minor increase in the totalthroughput time, so that, even if failures should occur during theremoval process, a high overall efficiency of the system in its entiretywill be possible.

Other advantageous embodiments, features and objects of the presentinvention can also be gathered from the detailed description, thedrawings and the attached claims following hereinbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional embodiments will now be described in more detail withreference to the attached drawings, in which:

FIG. 1a shows a schematic cross-sectional view of a teat rubber preform,which is produced on the basis of a suitable mould and which is to beremoved from at least one respective mould element in a subsequent workprocess,

FIG. 1b shows a schematic cross-sectional view of the preform which isin the process of being removed from a mould element, the radialexpansion of at least one tubular area of the teat rubber being limitedaccording to the present invention,

FIG. 1c is shows a schematic cross-sectional view of the teat rubberpreform which is in the process of being removed, a contact surface,which is partially adapted to the contour, being used for applying anaxial force,

FIG. 1d shows schematically an end portion of the teat rubber contactinga respective gripping element according to one embodiment,

FIG. 1e shows schematically a limiting device for determining themaximum radial expansion of the tubular area according to anotherembodiment, in the case of which the contour of the limiting surfacecorresponds essentially to that of the teat rubber,

FIGS. 1f and 1g show a schematic cross-sectional view of a sleeve forlimiting the radial expansion of the tubular area, the inner surface ofthe sleeve being provided with respective surface characteristics ofsuch a nature that the adhesion to, i.e. the friction with the teatrubber material is improved without any damage being caused to thepreform,

FIG. 1h shows a schematic cross-sectional view of a nozzle forintroducing a pressurized fluid according to an illustrative embodiment,

FIGS. 2a to 2c show a further embodiment of a part of a device forremoving teat rubber preforms, and

FIG. 2d shows schematically a device for processing a plurality of teatrubber preforms, a control unit being provided for supervising one or aplurality of process parameters.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1a shows schematically a sectional view of an injection mould 110having formed therein a preform 100 of a teat rubber consisting of asuitable polymer material mixture. The mould 110 is e.g. a component ofa respective injection system in which the desired polymer materialmixture is processed or prepared for introduction into the mould 110.For the sake of simplicity, the system in question is not shown. Themould 110 can have an arbitrary suitable structure for defining adesired size and shape of the preform 100. In particular, the mould 110can comprise appropriate mould halves 110 a, 110 b representingsubstantially the outer contour of the preform 100, whereas anappropriate mould element 110 c defines the inner contour of the preform100. It should be pointed out that the mould halves 110 a, 110 b can beimplemented e.g. as half shells or as cylinders, which are arrangedaround the mould element 110 c so as to define the final shape of thepreform 100. It should also be pointed out that an arbitrary number ofmould elements 110 a, 110 b can be provided and that they can have anarbitrary shape, provided that the desired size, shape and materialstrength of the preform 100 is accomplished.

During the production of the preform 100, a suitable polymer materialmixture, which is selected specifically with respect to the desiredproperties of the teat rubber, is processed and introduced in the mould110 under appropriate high pressure, said mould having possibly a hightemperature. According to an advantageous embodiment, the polymermaterial mixture is a silicone mixture, which will result in an improvedbehaviour during the milking process, as has been explainedhereinbefore. During introduction of the polymer material mixture intothe mould 110, respective parameters, such as pressure and temperature,can be varied, as will be advantageous for reliably filling the cavityformed in the mould 110 for the special material mixture. Process timesof from a few seconds to a few minutes may here be appropriate. When thepredetermined process time has ended, at least the mould halves 110 a,110 b will be removed automatically in a suitable manner, e.g. byopening respective gripper units and the like; depending on thestructural design of the mould 110 and on the process strategy, also apart of the mould element 110 c can be removed from a tubular area 100a, whereas a head area 100 b of the preform 100 will normally continueto adhere to the mould element 110 c.

FIG. 1b shows the preform 100 in a further process step; the preform 100comprising the tubular area 100 a and the head area 100 b adheres atleast to a part of the mould element 110 c and must therefore be removedfrom the mould element 110 c without any undesirable impairment of thematerial, i.e. part of the mould element 110 c may have been removedalready, as indicated by the dashed contour lines, so that the frontpart of the mould element 110 c, which is shown as a hatched area, holdsthe preform 100. In other cases, the mould element 110 c may be presentduring the removal in a substantially unchanged size. For this purpose,a suitable limiting device 150 is provided, which is implemented forlimiting to a predetermined range a radial expansion or widening of atleast the tubular area 100 a, whose material is normally thinner thanthat of the head area 100 b. To this end, the limiting device 150 isprovided with suitably implemented, limiting surface areas 151 which,when the interior of the tubular area 100 a has applied thereto apressurized fluid 161, will come into contact with the expandingmaterial of the preform 100, whereby further expansion will be preventedand an efficient separation of the material of the preform 100 from themould element 110 c will be effected. In the embodiment shown, e.g. anappropriate area or gap 152 can be seen, which predetermines a maximumexpansion of the tubular area 100 a. When soft polymer material mixturesare being processed, an application of the fluid 161 may have the effectthat an extreme expansion occurs at least in certain parts of thecomparatively thin-walled tubular area 100 a, so that such soft polymermixtures, e.g. silicone, are, in a conventional manner, normally notprocessed in respective automated systems immediately after moulding.The respective delimiting surfaces or surfaces 151 for limiting the area152 for the maximum radial expansion are so designed that they surroundat least large areas of the tubular area 100 a, a continuous envelopebeing, however, not necessary. In particular, suitable openings may beprovided, as will be explained in more detail herein-below, so as toavoid gas bubbles in the area 152 during expansion.

The surfaces 151 can be provided e.g. in the form of a suitable sleeve,e.g. in the form of a tube, the respective inner diameter of the sleevedefining in combination with the respective outer diameter of thepreform 100 the area 152. Hence, various sleeves can be provided so asto allow for various sizes of the preform 100, or a single size for thearea 152 can be chosen such that different preforms can be dealt with,without an irreversible deformation of the material occurring. Forexample, the size of the area 152 can be specified to be approx. 10 mm,whereby a total dimension of 20 mm is obtained; for many polymermaterial mixtures this will be a suitable value for avoiding anirreversible deformation in the case of standard diameters and materialstrengths of teat rubbers. The surfaces 151 may also be provided in theform of a plurality of surface elements, which, during the removalprocess, are arranged in a suitable manner in radially spacedrelationship with the preform 100 so as to define a suitable area 152 inthis way. It is not necessary to cover the whole area of the outersurface of the preform 100, provided that the respective non-coveredareas of the tubular area 100 a have lateral dimensions which preventthe material of the preform 100 from “bulging” when the fluid 161 isapplied thereto. The surfaces 151 can, for example, be provided in theform of shell-shaped elements, e.g. two shell halves, which are suitablypositioned during the process, the area 152 being adjustable to acertain extent by varying the respective distance in the case of someembodiments.

During the removal process, the interior of the tubular area 100 a hasapplied thereto the pressurized fluid 161 after positioning of thesurfaces 151 of the limiting device 150. Said fluid 161 can be anappropriate gas, e.g. pressurized air, or some other gas, e.g. nitrogen,for achieving by means of said gas a separation from the mould element110 c. In the case of some embodiments, the fluid 161 can also beprovided in the form of a liquid, provided that the limiting device 150is operated in suitable surroundings, so that the fluid 161 flowing outcan be discharged appropriately. When a soft material mixture is used inthe preform 100, the outer surface of at least the tubular area 100 awill, due to the high elasticity, be increasingly pressed against thesurface 151 due to the incoming fluid 161, and this will alsoincreasingly lead to a certain degree of separation of the material ofthe head area 100 b from the respective part of the mould element 110 c.For supporting the removal process and for generating a suitable fluidflow path leading out of the head area 100 b, which normally adherescomparatively firmly to a respective end plate 110 d of the mould 110, afew illustrative embodiments are so conceived that a suitable force isapplied by a device which is generally designated by reference numeral170 in FIG. 1b . This force, which is applied by said device 170 in asubstantially axial direction, causes a minor degree of separation ofthe material from the plate 110 d, i.e. deformation of the material onsaid plate 110 d, so that the fluid 161 can there flow out and thuscontribute to an additional, better separation from the mould element110 c. The device 170 can be used for continuing the application of therespective axial force so that the preform 100 can finally be separatedcompletely from the mould element 110 c. It follows that, afterinjection moulding, when the material of the preform 100 has still acomparatively high temperature, which may e.g. be higher than 150° C.,said material will not undergo an irreversible deformation, so that thecontour accuracy of the preform 100 will be preserved after the removalprocess and so that the final characteristics of the material can thenbe adjusted in a suitable manner during a subsequent treatment, e.g. bybaking out. In view of the automated and careful process of removing thepreform 100 from the mould element 110 c, said mould element 110 c canbe used immediately afterwards for a further production process ofanother preform, so that a high total throughput rate of the system willbe achieved, since especially the process of removal is typicallyexecuted much faster than the process of producing the preform 100,which may take a few 10 seconds up to a few minutes.

In the case of a few embodiments, the device 170 for applying the axialforce is mechanically coupled to the limiting device 150 in a suitablemanner, so that the non-positive connection occurring between thesurface 151 and the material of the preform 100 in response to anexpansion of the material of the tubular area 100 a can advantageouslybe utilized for applying a stronger force during the removal, at leastduring the initial phase of the removal process, when the pressureprevailing in the interior of the tubular area 100 a is stillsufficiently high. The adhesion of the head area 100 b to the mouldelement 110 c can thus be overcome effectively. For this purpose, thesurface 151 can be implemented in a suitable manner in such a way thatan increased adhesion, i.e. friction, will occur, as will be describedin more detail hereinbelow.

FIG. 1c shows a schematic representation of the preform 100 during theremoval process, the device 170 being provided with appropriate contactsurfaces 171 whose contour corresponds to that of the head area at leastalong a part of the latter. In the embodiment shown, in particular alsothe outer contour of the head area 100 b is designed in such a way thata comparatively strong axial force can be transmitted during the removalof the preform 100. In addition, the surfaces 171, which substantiallyimitate the shape of the head area 100 b, can be used for providing acomparatively large contact area and, consequently, a comparativelylarge force-application area, so that, on the one hand, undesirabledamage can be avoided during contact with the head area 100 b and sothat, on the other hand, the desired high force will be available duringthe removal process. Furthermore, at least during the initial phase ofthe removal process, also the contact with the surface 151 can, asindicated by the broken line, contribute to an efficient non-positiveconnection between the preform 100 and the device 170, as has beenexplained hereinbefore.

FIG. 1d shows a schematic representation of an end portion 100 c of thepreform 100, an additional device 180 being provided, which hasrespective surfaces 181 that can be brought into contact with thematerial of the preform 100. To this end, the surfaces 181 can have anarbitrary suitable shape; their shape can e.g. correspond to that of apossibly contoured surface design of the end portion 100 c, so that, dueto the effect produced by the device 180, a mechanical fixing of the endportion 100 c will be accomplished. Due to the improved mechanicalfixing of the end portion 100 c, the fluid 161 can be introduced under adesired high pressure, since the leak tightness of the end portion 100 cwill be improved in spite of the pressure applied through the fluid 161.In an illustrative embodiment, the end portion 100 c is thereforeimplemented in such a way that an efficient mechanical fixing of thesurfaces 181 can be accomplished. This can be achieved by an appropriateconfiguration of the preform 100 and a suitable structural design of thesurfaces 181.

FIG. 1e shows a schematic representation of the preform 100 incombination with the limiting device 150 according to anotherembodiment. In this embodiment, the surfaces 151 for limiting the radialexpansion of the preform 100 correspond to the outer contour of thepreform 100 over large areas of the latter, so that the area 152 isprovided in the region of the tubular area 100 a, whereas in the regionof the head area 100 b a contact is established with the material of thepreform 100, when no pressure is applied, or the spacing in question ismuch smaller so that a non-positive connection will be establishedduring the removal process. In this way, a frictional connection betweenthe limiting device 150 and the preform 100 will be accomplished over avery large area in response to an application of pressure, so that, inthis case, the limiting device 150 can also serve as the device 170 forapplying an axial force to the preform 100 in an efficient manner. Itfollows that, in this embodiment, the limiting device 150 can have ashape similar to that of the mould 110 (cf. FIG. 1a ), but, other thanin the case of the mould 110, an appropriate gap for producing thedesired area 152 has to be provided in the tubular area 100 a. Inaddition, suitable gas outlets 155 can be provided, so that theformation of gas bubbles during the expansion of the material of thepreform 100 will be avoided to a very large extent, as has already beenexplained hereinbefore. According to other embodiments, the limitingdevice 150 is provided such that it extends over large areas of thepreform 100, but it does not necessarily extend over the whole preform100, provided that the necessary axial force can be transmitted to thepreform 100 during the removal process. During the removal process, thelimiting device 150 is, e.g. in the form of two semi shells, moved closeto the preform 100 and is then closed in a suitable manner so that thefluid 161 can then be introduced under the desired pressure;simultaneously, an axial force can be executed by the limiting device150 so as to support the separation of the preform 100 from the mouldelement 110 c. By designing this embodiment of the limiting device 150in the manner shown in FIG. 1e , also very long preforms 100 canreliably be removed from the respective mould element 110 c, since theaxial force that can be applied in combination with a high pressure is,in its entirety, very high. This is particularly advantageous in caseswhere the tubular area 100 a comprises a tubular part which projectsbeyond standard teat cups, a mode of arrangement that can be usedadvantageously in many milking equipment. In this way, both the teatrubber and the milk hose following said teat rubber can be produced inone working process making use of a very soft material, e.g. silicone.

The device 150 according to FIG. 1e can, as has already been describedin connection with the preceding embodiments of said device, be composedof a plurality of separate parts, which will then be united on thepreform 100 in a suitable manner for the removal process, so that thepreform 100 will be enclosed.

The enlarged detail in FIG. 1e shows the situation at one of the gasoutlets 155 when the fluid 161 is being introduced, so that the materialof the tubular area 100 a is pressed against the surface 151 and intothe gas outlet 155. This results in the formation of a bulge 100 d whichleads to an interlocking engagement with the surface 151. In thisembodiment, the effective entrance area of the gas outlet 155 has beenchosen such that the bulge 100 d is formed for the special conditions inquestion, i.e. the pressure of the fluid 161, the thickness and thematerial strength of the polymer mixture of the tubular area 100 a, thetemperature of the latter, and the like, the deformation occurring beingonly of a reversible nature so that, after the removal process, theoriginal shape will be reestablished. In the case of other embodiments,the size and the shape of the gas outlets 155, i.e. their entrance area,is chosen such that no bulge that would be worth mentioning is formed.The appropriate size and shape of the entrance area for avoiding anirreversible deformation can be ascertained by executing tests undervarious conditions. The gas outlets 155 may have an arbitrary shape andassume the form of e.g. gaps, holes, etc., provided that theabove-mentioned conditions with respect to the bulge 100 d are observed.

The above-explained aspects concerning the gas outlets 155 also apply tothe embodiments which have already been described with reference to FIG.1b to 1d as well as to all the other embodiments.

FIG. 1f shows a schematic representation of a cross-section of a part ofthe limiting device 150 according to an illustrative embodiment, inwhich the surface 151 is patterned in a suitable manner, e.g. by meansof appropriate raised portions 153 and the like, so that, in total, anefficient non-positive connection is accomplished between the materialof the preform 100 and the surface 151 when high pressure is applied.The respective surface topography, e.g. the raised portions 153, can beimplemented in a suitable manner for allowing a high adhesion, i.e.friction for the material mixture to be processed, without causing anydamage thereto. For example, a distinct surface topography may beprovided for soft material mixtures, whereas an appropriate smoothsurface will be provided for hard material mixtures.

FIG. 1d shows a schematic representation of a part of the limitingdevice 150, the surface 151 being here defined by a suitable materiallayer which, in combination with the material mixture of the preform100, guarantees an appropriately high adhesion. This allows a highdegree of flexibility in the selection of the “carrier material” 151 afor the surface 151 for which an arbitrary material can then be used,without having to consider other characteristics, such as mechanicalrobustness, etc., since the carrier material 151 a will provide themechanical stability of the surface 151. It is, by way of example, alsopossible to provide different surface materials 151, e.g. in the form ofthin tubes, etc., which are then inserted into the carrier tube 151 andsecured in position, so as to allow for different material mixtures forthe preform 100.

FIG. 1h shows a schematic representation of the end portion 100 c incombination with a device 160 for introducing the fluid 161 according toan illustrative embodiment. The device 160 for introducing the fluid 161comprises, according to the present embodiment, a nozzle 162 which isconnected to a suitable pressure reservoir (not shown) for the fluid 161by means of a connection line 163. In the embodiment shown, the device160 additionally comprises suitable sealing surfaces 164, which, whenthe pressurized fluid 161 is applied to the preform 100, accomplish ahigh degree of leak tightness, even if the end portion 100 c shouldexpand to a certain degree, i.e. the obliquely extending sealingsurfaces 164 have the effect that an increasing counterforce will begenerated in response to a pressure-induced expansion of the end portion100 c, so that good sealing characteristics will be obtained. Inaccordance with another illustrative embodiment, the nozzle 162,together with the respective sealing surfaces 164, is adapted to bemoved mechanically relative to the end portion 100 c in the axialdirection designated by reference numeral 165, so that a contact forceof the nozzle 162, i.e. of the sealing surface 164, can be adjusted in asuitable manner, irrespectively of the other components, e.g. thelimiting device 150. It is thus possible to attach the sealing surface164 with a suitable axial force to the end portion 100 c during theremoval process, and to introduce the fluid 161 under a suitably highpressure, the increased contact pressure guaranteeing a high leaktightness and, consequently, the maintenance of the high operatingpressure. This allows an efficient removal also in the case of preformshaving a comparatively high adhesion in view of their respective overalllength or in view of process fluctuations of the preceding injectionprocess. In particular, it is possible to adjust, in connection with anappropriate control unit, the contact force and/or the fluid pressure,so that the process can be adapted to different operating conditions ina flexible manner.

FIG. 2a shows a schematic perspective representation of a part of adevice 290 for removing a preform from a component of the mould, saiddevice 290 comprising at least some of the components which have beendescribed hereinbefore with reference to FIG. 1a to 1h . The removaldevice 290 includes a removal unit 270 comprising, in the embodimentshown, two halves of a contoured surface 271, which serve as contactsurfaces so as to establish a frictional connection with the material ofthe head area of the preform for applying thus an axial force forremoving the preform, as has also been described hereinbefore. In theembodiment shown, the removal unit 270 is composed of two halves, whichare mounted on suitable mechanical components 272 that allow a radialmovement of the surfaces 271 and a respective axial movement. Themechanical components 272 can be realized by arbitrary suitable actuatorcomponents, such as pneumatic, hydraulic, electric or other componentsor combinations thereof. In addition, the device 290 comprises alimiting device 250 provided e.g. in the form of a tubular sleeve 254having provided therein respective gas outlets 255, as has already beenexplained in connection with FIG. 1e . Furthermore, a gripping means 280is provided, which, via respective surfaces 281, is adapted to bebrought into contact with the end portion of a respective preform, thesleeve 254 of the limiting device 250 being provided with appropriaterecesses 256 for this purpose. In addition, an appropriate fluidintroduction means is provided, which cannot be seen in FIG. 2a . Thefluid introduction means can be provided with a suitable nozzle which,in the embodiment shown, can e.g. be connected to the limiting device250, whereas in the case of other embodiments a nozzle is provided,which allows a movement relative to the sleeve 254, as has beenexplained e.g. in connection with the fluid introduction device 160 inFIG. 1 h.

FIG. 2b shows a schematic representation of a top view of a part of thedevice 290, the contact surfaces 271 and the contact surfaces 281 whichare in the coupled state in the present embodiment—said contact surfaces271 and 281 thus representing a first gripping means and a secondgripping means—being shown in an “open” condition, so that the device290 can be positioned over the respective tubular area of a preform, assoon as the respective preform is available.

FIG. 2c shows a schematic perspective representation of the removaldevice 290 according to another illustrative embodiment in which theremoval unit 270 with the respective contoured surfaces 271 is providedwith a further gripping means 275 which, via respective contactsurfaces, is adapted to be brought into contact with the material of thepreform through appropriate openings 256 in the sleeve 254. Hence, thecontact surfaces 271, the additional gripping means 275 and the means280 are provided for contacting the preform directly, at least thecontour of the surfaces 271 corresponding to that of the preform in thearea in question, e.g. the head area. It follows that the removal device290 is implemented for efficiently removing also preforms ofcomparatively great length from a respective mould element, since acomparatively strong axial force and also a high operating pressure canbe built up in the preform, a maximum radial expansion being efficientlylimited by the limiting device 250, as has been explained hereinbefore.In particular, the removal device 290 can have provided therein a fluidintroduction means which is adapted to be moved relative to the endportion of the preform, as has e.g. be explained in connection with themeans 160 according to FIG. 1h , so that a necessary high operatingpressure can be built up.

FIG. 2d shows a schematic representation of the removal device 290according to another illustrative embodiment in which a plurality ofpreforms 200 a, . . . , 200 d can be processed simultaneously. For thispurpose, respective units of the device 290 are provided, each unitincluding a removal unit 270 a, . . . , 270 d, a limiting device 250 a,. . . , 250 d, and a fluid introduction means 260 a, . . . , 260 d. Inaddition, the removal device 290 has provided therein a control unit 220which adjusts process parameters, e.g. the respective fluid operatingpressure to be used in the individual units, and the magnitude of theaxial force applied during the removal. This force can be selected suchthat it has the same magnitude for all units, when these units aremechanically coupled to one another in a rigid mode of connection, or itcan be controlled individually; in this case, appropriate individuallymovable actuator units are provided. In addition, some embodiments canbe so conceived that a relative movement of the respective fluidintroduction means 260 a, . . . , 260 d is individually controllable, ashas been described e.g. in connection with the fluid introduction means160 in FIG. 1h . In accordance with another illustrative embodiment, oneor a plurality of sensor elements 221 a, 221 d is/are provided andpositioned such that the presence of a preform in the respective unitsof the removal device 290 can be detected by means of the control unit220. The sensor units 221 a, . . . , 221 d may e.g. record suitablevalues, such as the temperature, optical characteristics, electriccharacteristics, acoustic characteristics (ultrasound) and the like,which allow conclusions to be drawn with respect to the presence or theabsence of a respective preform.

When the removal device 290 is in operation, the respective limitingdevices 250 a, . . . , 250 d are adequately positioned over the preforms200 a, . . . , 200 d, which adhere to the respective mould elements 210a, . . . , 210 c after the production, and the removal units 270 a, . .. , 270 d are activated in interaction with the fluid introduction means260 a, . . . 260 d so as to initiate the above-described removalprocess. Following this, an axial movement of the device 290 is executedfor removing the respective preforms 200 a, . . . 200 d. After theremoval process, the respective preforms 200 a, . . . 200 d can beconveyed, e.g. by means of the device 290 to a suitable transfer sitewhere the preforms are collected and subjected to further processing. Itis, for example, possible to adequately adjust the final materialcharacteristics of the preforms 200 a, . . . , 200 d by a subsequentheat treatment so that the final molecular structure of the polymermaterial, e.g. of the silicone, will be obtained. The heat treatment canbe executed for a plurality of preforms at the same time, so that theprocess throughput during the production of the respective teat rubbersonly depends on the capacity of the respective injection mouldingsystem. Hence, a plurality of preforms can be processed simultaneously.If necessary, the process conditions can be adjusted individually, ife.g. the individual units of the removal device comprise individuallycontrollable components, such as valves for the fluid pressure,mechanical actuators, etc.

During the removal process, different degrees of adhesion between therespective preforms and the mould element in question may occur due todifferences in the process, so that one or a plurality of removalprocesses may perhaps fail. In the example shown, the preform 200 a isnot successfully removed. In the case of one embodiment, the absence ofthe preform 200 a in the device 290 is detected on the basis of thesensor element 221 a via the control unit 220. The control unit thenexecutes an appropriate correction function in accordance with apredetermined operational sequence, said correction function consistinge.g. in a report to the operator of the system 290. In accordance withanother illustrative embodiment, the removal process is repeated, whenthe removed preforms 200 b, . . . , 200 d have been transported away.One embodiment is e.g. so conceived that units of the removal device 290which are not needed can be deactivated by the control unit 220, whereasspecial process parameters can be applied to the removal unit 270 a andthe fluid introduction means 260 a. For example, the control unit 220can cause an increase in the operating pressure of the fluid introducedby the means 260, so as to increase the efficiency of the removalprocess. Following this, the removal of the preform 200 a can beexecuted, and, if also this attempt should fail, additional correctivemeasures can be taken. The finally removed preform 200 a can then beconveyed or rejected, if, due to the parameter adjustment used duringthe removal process, it must be expected that damage may have beencaused to the preform 200 a. Since the removal process and thesubsequent conveying process for depositing the preforms are normallymuch shorter than the respective preform production process, even anunsuccessful removal of one of the preforms will only result in a minorreduction of the overall throughput, so that a high overall throughputcan be maintained while guaranteeing simultaneously a high degree ofautomation and operational reliability.

It follows that, according to the present invention, pressure is appliedwhen the teat rubber preforms are removed during the production of teatrubbers, in particular of teat rubbers containing a high percentage ofsilicone, the radial expansion of teat rubber areas being appropriatelylimited to a maximum value. Hence, the removal can be executedautomatically and at a comparatively high temperature withoutirreversible damage being caused to the material. The removal processcan be supported by an appropriate contact surface whose contourcorresponds, at least partially, to the outer contour of the preform.

While the present invention has been described with respect to severaldifferent embodiments, it will be obvious that various modifications maybe made without departing from the spirit and scope of this invention.

What is claimed is:
 1. Device for removing a preform of a teat rubberwhich has a head region with a contour and a tube region and is appliedat least partially to an element determining the inner shape of the teatrubber, said device comprising: a removal unit with a shaped contactface adapted to the contour of the head region which is to be brought atleast partially into contact with the head region of the preform, afluid introduction means which is embodied for introducing a pressurizedfluid into the tube region, and limiting means for limiting the radialexpansion of the tube region on introduction of the fluid, wherein theshaped contact face is modelled on the contour of the preform and inthat a traction mechanism is provided for exerting a tensile force onthe preform via the shaped contact face in the direction of thelongitudinal axis of the preform.
 2. Device according to claim 1,wherein the limiting means has a sleeve which at least partiallysurrounds the tube region to define a gap between the exterior and aninner face of the sleeve for limiting the radial expansion.
 3. Deviceaccording to claim 1, wherein the limiting means is embodied to limitthe radial expansion to 20 mm or less.
 4. Device for removing a preformof a teat rubber which has a head region and a tube region and isapplied at least partially to an element determining the inner shape ofthe teat rubber, said device comprising: a removal unit with a contactface which is to be brought at least partially into contact with thepreform, a fluid introduction means which is embodied for introducing apressurized fluid into the tube region, and limiting means for limitingthe radial expansion of the tube region on introduction of the fluid,wherein the contact face is modelled on the contour of the preform andin that a traction mechanism is provided for exerting a tensile force onthe preform via the contact face in the direction of the longitudinalaxis of the preform, wherein the limiting means has a sleeve which atleast partially surrounds the tube region to define a gap between theexterior and an inner face of the sleeve for limiting the radialexpansion, and wherein the sleeve has gas outlets which substantiallyprevent the production of gas pockets between the inner face of thesleeve and material of the tube region during the radial expansion. 5.Device according to claim 1, wherein the limiting means has, during aradial expansion of the tube region a surface which enters into contactwith the tube region and has a surface property promoting adhesionand/or friction.
 6. Device according to claim 1, wherein the limitingmeans further has a nozzle, which is axially movable relative to theelement, for introducing the fluid.
 7. Device according to claim 6,wherein a press-on force of the nozzle is adjustable during contact withthe tube region.
 8. Device according to claim 5, wherein the surfaceforms part of the shaped contact face.
 9. Device according to claim 1,wherein the limiting means has limiting faces which, in the operatingposition for removing the preform, are modelled on the outer contour andform, at least in the tube region, a defined gap for expansion. 10.Device according to claim 9, wherein the limiting faces have a pluralityof face elements which can be positioned by gripper elements in theoperating position for removal.
 11. Device according to claim 1, whereinthe shaped contact face has at least a first contact face region forcontacting a head region of the preform and a second contact face regionfor contacting an end region of the preform.
 12. Device according toclaim 11, wherein the first contact face region is formed by the surfaceof jaws of a first gripping means and the second contact face region isformed by the surface of jaws of a second gripping means.
 13. Deviceaccording to claim 11, wherein a third contact face region is providedthat is arranged, in the longitudinal direction of the tube region,between the first and the second contact face region.
 14. Deviceaccording to claim 2, wherein the inner face of the sleeve is modelledat least partially on the contour of the preform to be removed. 15.Device according to claim 1, embodied to remove a plurality of preformssimultaneously.
 16. Device according to claim 1, further having acontrol unit which is embodied to keep the fluid pressure and a tensileforce exerted during removal in a specified range.
 17. Device accordingto claim 16, wherein the control unit is further embodied to detect anon-removed preform and to carry out a specified correction function.18. Device according to claim 17, wherein the correction functionincludes repeating the removal process.
 19. Device according to claim 1,further embodied to exert an axial force on the tube region compressingat least the tube region in order to assist the detachment of thematerial of the preform from the element.
 20. Device according to claim19, wherein the removal unit, the fluid introduction means, and thelimiting means are jointly movable to exert the axial force.
 21. Adevice for removing a preform of a teat rubber having a head region witha shape and a tube region from a mold having a longitudinal axiscomprising: a sleeve placed around the tube region forming a radial gapbetween said sleeve and the tube region limiting radial expansion of thepreform; a fluid supply adjacent the tube region, wherein pressurizedfluid is applied to an interior of the tube region radially expandingthe preform away from the mold; and a removal unit having a shapedcontact surface conforming to the shape of the head region and movablealong the longitudinal axis, whereby the shaped contact surfaceconforming to the shape of the head region assists in removing thepreform from the mold without deforming or damaging the preform whensaid removal unit is moved along the longitudinal axis.
 22. A device forremoving a preform as in claim 21 further comprising: fluid outletsformed in said sleeve, whereby fluid pockets are prevented from formingadjacent said sleeve when the tube region radially expands.